Sunday's lack of penalties continues a trend since the league clarified the new rule on Aug. 22, which noted that "inadvertent or incidental contact with the helmet and/or facemask is not a foul."

During the first two weeks of preseason action, 51 helmet penalties were called. After the clarification, only 20 were called in the final two weeks of the preseason.

The new rule, which is designed to enhance player safety by removing the technique of lowering the head to initiate and make contact with an opponent, had been a source of confusion for players and coaches this preseason.